Box fan grill with integral motor support

ABSTRACT

A box fan with a motor and impeller that is supported by a polymer grill is provided. The device may include a metal body and at least one polymer grill, a motor and an axial air impeller. The motor being structurally supported by the polymer grill.

CROSS-REFERENCE APPLICATIONS

This application claims priority to provisional patent application60/829,766 filed Oct. 17, 2006.

TECHNOLOGY FIELD

The present invention relates to an air moving apparatus. Morespecifically, the present invention relates to the motor mountingstructure utilized on a conventional box fan.

BACKGROUND

The box fan has been in existence for many years. The box fan has provenitself to be one of the most versatile air moving devices, sellingnumerous millions of units every year. Because of its popularity therehas been constant pressure on the manufacturer to produce the box fanless expensively without compromising the safety or the quality of thefinal product.

One manner to effectively achieve this goal is to reduce the materialusage and by default the raw material cost needed to produce the device.The use of motor production technology, plastic materials, sizereduction etc. have all yielded cost reductions for the box fan over theyears.

What is needed are further innovations in the box fan structure thatwill maintain or improve the quality and safety of the device while atthe same time allow the manufacturer the ability to produce the deviceat a lower cost. The lower cost will enhance the appeal of the item to agreater number of users.

SUMMARY

The present invention is directed to embodiments of a box fan thatutilizes a motor mounting structure incorporated into a polymer reargrill of the device. The utilization of the polymer grill in this mannereliminates the need for metal brackets and the additional labor neededto assemble the metal brackets in the construction of a conventional boxfan. This reduces the cost of the box fan to the consumer and allows theproduct to be more affordable to a wider range of users and moreprofitable to the manufacturer. Another advantage of the describeddevice is the ability of the polymer rear grill to electrically isolatethe motor of the device from external metal components such as the bodyof the box fan.

In accordance with one embodiment, a box fan includes a fan body formedof metal comprising at least one wall forming a substantially polygonalshape having a rear body opening and a front body opening. The front andrear openings are substantially parallel to one another and are locatedon the opposite side of the fan body. A unitary rear grill formed ofpolymer may be disposed proximate and substantially covering the rearbody opening. The unitary rear grill includes a perimeter rail definingextents of the unitary rear grill, a plurality of grill elementsdefining flow through openings that allow air to pass through theunitary rear grill, and an integrated motor interface structuresubstantially centered with reference to the extents of the unitary reargrill. The box fan includes a front grill disposed proximate andsubstantially covering the front body opening. An interior space isdefined by the at least one wall of the fan body, the unitary reargrill, and the front grill. A motor having a shaft extension is disposedwithin the interior space. The motor is connected to and structurallysupported by the integrated motor interface structure of the unitaryrear grill. An axial air impeller is disposed within the interior space.The air impeller includes a hub connected to the shaft extension of themotor, and a plurality of blades extending radially outward from thehub.

According to one aspect of the invention, the unitary rear grillincludes support channels extending from the motor interface structureto the perimeter rail of the unitary rear grill. The support channelsstructurally support the motor and the axial air impeller. The supportchannel may define a conduit and control wires of the box fan may belocated in the conduit. The support channel may include at least onewall defining a recess.

According to another aspect of the invention, the at least a portion ofthe plurality of grill elements extend from the motor interfacestructure to the perimeter rail of the unitary rear grill. This portionof the plurality of grill elements functions, in part, to structurallysupport the motor and the axial air impeller.

According to another aspect of the invention, the unitary rear grillcomprises a spherical form as defined by a surface of the rear grill,wherein the surface comprises a spherical radius.

According to another aspect of the invention, the motor includes a rearend bell having ventilation openings. The integrated motor interfaceincludes a motor mounting surface, and a cooling opening substantiallycentered in the motor mounting surface. The ventilation openings of therear end bell and the cooling opening in the integrated motor interfacemay be substantially aligned.

According to another aspect of the invention, the hub of the axial airimpeller further comprises a first circumferential periphery and themotor mounting surface is defined by a second circumferential periphery.The first and the second circumferential peripheries may besubstantially aligned.

According to another aspect of the invention, the integrated motorinterface structure further comprises a plurality of motor mountingholes for receiving fasteners to secure the motor to the integratedmotor interface structure.

According to another aspect of the invention, the perimeter rail, grillelements, motor interface, and support channels are a single moldedpolymer part. The single molded polymer part electrically isolates themotor from all external surfaces of the box fan.

According to another aspect of the invention, the perimeter railincludes: a first wall substantially parallel to the grill elements; asecond wall extend substantially orthogonal and outward from the firstwall; and a third wall extending substantially orthogonal from thesecond wall.

According to another aspect of the invention, the rear grill perimeterrail includes: a first wall substantially parallel to the grillelements; a second wall extending outward from the first wall; a recessformed in the second wall; a third wall extending from the second wall,the third wall oriented substantially orthogonal to the first wall; andangular ribs extending between the first wall and the third wall, theangular ribs connecting the first wall, the second wall, and the thirdwall.

According to yet another aspect of the invention, the rear grill furtherincludes: horizontal structural supports extending from the integratedmotor interface to sides of the perimeter rail; and vertical structuralsupports extending from the integrated motor interface to a top and abottom of the perimeter rail. The horizontal structural supports and thevertical structural supports may be constructed dimensionally thickerthan the grill elements.

According to another aspect of the invention, the rear grill includes: aplurality of substantially concentric arcuate grill elements; and radialstructural supports extending radially from the integrated motorinterface to the perimeter rail. The radial structural supports may beconnected to the concentric arcuate grill elements.

According to another embodiment of the invention, a box fan includes afan body formed of metal. The fan body includes at least one wallforming a substantially polygonal shape having a rear body opening and afront body opening. The rear and front openings are substantiallyparallel to one another and located on the opposite sides of the fanbody. A unitary rear grill may be formed of polymer and may be disposedproximate and substantially covering the rear body opening. The unitaryrear grill includes a perimeter rail defining extents of the unitaryrear grill. The unitary rear grill also includes a plurality of grillelements defining flow through openings, the flow through openingsallowing air to pass through the unitary rear grill. The unitary reargrill further includes a substantially circular-shaped integrated motorinterface structure substantially centered with reference to the extentsof the unitary rear grill. Moreover, the unitary rear grill includessupport channels extending between and connecting the motor interfacestructure to the perimeter rail of the unitary rear grill. The box fanalso includes a front grill disposed proximate and substantiallycovering the front body opening. An interior space is defined by the atleast one wall of the fan body, the unitary rear grill, and the frontgrill. A motor is disposed within the interior space, the motor beingconnected to and structurally supported by the integrated motorinterface structure of the unitary rear grill. The motor also has ashaft extension. An axial air impeller is disposed within the interiorspace. The air impeller includes a hub connected to the shaft extensionof the motor and a plurality of blades extending radially outward fromthe hub.

According to yet another embodiment of the invention, a box fan includesat least one wall formed of metal forming a substantially polygonalshape. Rear and front openings are formed by the at least one wall. Therear and front openings are oriented substantially parallel to oneanother and are located on the opposite sides of the at least one wall.A front grill is disposed proximate and substantially covering the frontopening. The front grill includes a plurality of front grill elementsdefining front flow through openings that allow air to pass through thefront grill. A rear grill is disposed proximate and substantiallycovering the rear opening. A perimeter rail defines extents of the reargrill. The rear grill includes a plurality of rear grill elementsdefining rear flow through openings that allow air to pass through therear grill. The rear grill also includes a substantially circular shapedintegrated motor interface structure substantially centered withreference to the extents of the rear grill. Motor cooling openings maybe provided in a center region of the integrated motor interfacestructure. Support channels may extend outward from the motor interfacestructure and connect to the perimeter rail. The rear grill, theperimeter rail, the rear grill elements, the motor interface, and thesupport channels are preferably formed as a single molded polymer part.An interior space is defined by the at least one wall of the fan body,the front grill, and the rear grill. A motor is disposed within theinterior space and may be connected to and structurally supported by theintegrated motor interface structure of the rear grill. The motorincludes a shaft and a rear end bell. Ventilation openings may beprovided in the rear end bell. Preferably, the ventilation openings ofthe motor rear end bell substantially align with the motor coolingopenings in the integrated motor interface structure. An axial airimpeller is disposed within the interior space. A substantially circularshaped hub of the air impeller connects to the motor shaft. Acircumference of the substantially circular shaped hub may besubstantially equal to the substantially circular shaped integratedmotor interface structure. A plurality of blades of the air impellerextend radially outward from the hub.

The use of the polymer rear grill to support the motor can incorporateother features within the structure such as, for example: handles,switches, improved cooling features, etc. These features combined withthe incorporation of the motor support into the rear polymer grill ofthe box fan yield further cost savings for the user.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read in connection with the accompanying drawings. It is emphasizedthat, according to common practice, the various features of the drawingsare not to scale. On the contrary, the dimensions of the variousfeatures are arbitrarily expanded or reduced for clarity. Included inthe drawings are the following Figures:

FIG. 1 is a rear perspective view of an exemplary box fan in accordancewith embodiments of the present invention;

FIG. 2 is a front perspective exploded view of the exemplary box fan ofFIG. 1;

FIG. 3A is a rear perspective view illustrating an embodiment of a grillof the present invention;

FIG. 3B is a partial cross section through a support channel of thegrill embodiment of FIG. 3A;

FIG. 3C is a partial cross section view through the a perimeter rail ofthe grill embodiment of FIG. 3A;

FIGS. 3D and 3E are a partial cross sectional view and a partial frontview respectively of an alternate embodiment for the perimeter rail;

FIG. 4 is a rear perspective view illustrating an alternative structurefor an embodiment of a grill of the present invention;

FIG. 5 is a rear perspective view illustrating another alternativestructure for an embodiment of a grill of the present invention;

FIGS. 6A, 6B and 6C are rear, top and side views of another embodimentof the present invention; and

FIG. 7 shows another embodiment of the present invention in conjunctionwith various incorporated features.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1 is a rear perspective view of box fan 100. As shown, box fan 100includes rear grill 110, front grill 150 and body 120. Body 120 may befabricated of metal and is generally polygonal in shape. In a preferredembodiment, body 120 includes four surfaces 120 a arranged in twosubstantially parallel sets, the first substantially parallel set ispositioned substantially orthogonal to the second substantially parallelset. For example, the first substantially parallel set may be positionedhorizontally and the second substantially parallel set may be positionedvertically. In a preferred embodiment, corners 120 b where orthogonalsurfaces 120 a meet are arcuate in form. It is contemplated that othershapes and/or non-arcuate corners can be utilized as alternativeembodiments of corners 120 b.

Rear grill 110 is fabricated of polymer and is substantially planar inform. As shown in this example, the substantially planar form of reargrill 110 is positioned substantially orthogonal to all surfaces 120 aof body 120. Also as shown, front grill 150 is substantially planar inform and is positioned substantially parallel to rear grill 110 on theopposing side of body 120.

As shown, body 120, rear grill 110 and front grill 150 define interiorspace 123. Disposed within interior space 123 is electric motor 130 andaxial air impeller 140. Electric motor 130 rotates axial air impeller140 causing air to enter interior space 123 through either rear grill110 or front grill 150. The air is accelerated and exits interior space123 as an exhaust air flow through either rear grill 110 or front grill150.

Also shown in FIG. 1 is handle 160 and control 162. Handle 160 is usedto facilitate the portability of box fan 100. Control 162 controls afunction of box fan 100, such as, for example, the rotational speed ofelectric motor 130 and axial air impeller 140.

Power cord 105 may be utilized to connect box fan 100 to an electricalpower source (i.e. wall outlet). The electrical component connections ofbox fan 100 are integrated within the device, such as, for example,between control 162 and motor 130. The integration of the electricalcomponent connections within the device eliminates the need for the userto make such connections. In the exemplary embodiment shown, only theconnection of power cord 105 to an electrical power source is requiredfor operation of box fan 100.

Preferably, power cord 105 utilizes a safety plug. Details of the safetyplug and its advantages can be referenced in U.S. Pat. No. 6,793,535,which is hereby incorporated into this patent application in itsentirety.

FIG. 2 is a front perspective exploded view of box fan 100 of FIG. 1. Asshown, body 120 includes front perimeter lip 128 a and rear perimeterlip 128 b. Front body opening 124 as shown, is defined by frontperimeter lip 128 a. Rear body opening 122 may similarly be defined byrear perimeter lip 128 b. Located on both front and rear perimeter lips128 a and 128 b are holes 126. Holes 126 are used to attach front andrear grills, 150 and 110 respectively, to body 120. It is contemplatedthat assembly devices (not shown) such as, for example, screws may beutilized via holes 126 in body 120 and holes 153, 113 of front and reargrills, 150 and 110 respectively, to assemble front and rear grills 150and 110 to body 120. It is further contemplated that other assemblydevices such as adhesives or snaps may be used to assemble front grill150 and rear grill 110 to body 120. Interior space 123 of box fan 100 isdefined by the assembly of body 120, front grill 150 and rear grill 110.

Front grill 150 may include, as shown, perimeter rail 152. Perimeterrail 152 defines the planar extents of front grill 150. Vertical andhorizontal grill elements 156 are located within the planar area definedby perimeter rail 152. Grill elements 156 are designed to minimize theirimpedance to the flow of air into and/or exiting box fan 100 while atthe same time protecting box fan 100 from the penetration of foreignobjects into interior space 123.

As shown, rear grill 110 may include perimeter rail 112. Perimeter rail112 defines the planar extents of rear grill 110. Vertical andhorizontal grill elements 116 are located within the planar area definedby perimeter rail 112. Grill elements 116 are designed to minimize theirimpedance to the flow of air into and/or exiting box fan 100 while atthe same time protecting box fan 100 from the penetration of foreignobjects into interior space 123. Rear grill 110 also includes motorinterface 118 and support channels 114. As shown, support channels 114extend from motor interface 118 outward to perimeter rail 112. In apreferred embodiment, perimeter rail 112, grill elements 116, motorinterface 118 and support channels 114 are a single molded polymer part.

As shown, electric motor 130 and axial air impeller 140 are disposedwithin interior space 123. Electric motor 130 is attached to motorinterface 118 of rear grill 110 via motor mounting holes 111. It iscontemplated that assembly devices, (not shown) such as, for example;screws can be utilized via motor mounting holes 111 to assemble electricmotor 130 to rear grill 110. It is further contemplated that otherassembly devices such as adhesives or snaps may be used to assembleelectric motor 130 to rear grill 110.

Electric motor 130 may include at least one shaft 132, rear end bell134, front end bell 136 and ventilation openings 138 in both rear endbell 134 and front end bell 136. Axial air impeller 140 is attached toshaft 132 and rotated by electric motor 130.

Axial impeller 140 may include hub 142 and multiple blades 144. Asshown, hub 144 has a circular form. The rotation of axial air impeller140 generates and exhaust air flow, as described with reference to FIG.1.

It can be appreciated that assembling electric motor 130 to rear grill110 has an advantage of electrically isolating electric motor 130 fromall external surfaces of box fan 100. This advantage serves to providegreater safety for the user when compared to conventional box fans thatutilize metal mounting brackets. It can also be seen that assemblingelectric motor 130 to rear grill 110 has a manufacturing advantage ofeliminating the metal motor mounting brackets commonly used on aconventional box fan. The elimination of the metal brackets not onlyeliminates the material required to fabricate the metal brackets, butalso eliminated the assembly process and labor associated with attachingthe metal brackets to body 120. The material and assembly costreductions combined with the additional safety of box fan 100 enhancemarketability when compared to a conventional box fan.

Also shown in FIG. 2 are handle 160 and control 162. As shown, handle160 is attached to body 120 through holes 125 located in body 120. Itcontemplated that assembly devices such as adhesives, snaps or screwsmay be used in conjunction with holes 125 to attach handle 160 to body120. Control 162 may include such items, (not shown) such as switches,knobs, thermostats, LEDs and power control boards. It is alsocontemplated that a remote control may be used in lieu of and/or inconjunction with control 162. Control 162 may be external to body 120and/or partially located within interior space 123 of body 120. Asshown, passage 127 permits control 162 to access both internal space 123and exterior of body 120.

FIG. 3A is a rear perspective view of rear grill 110. As shown, in apreferred embodiment perimeter rail 112 includes at least six holes 113used to assemble rear grill 110 to body 120 of box fan 100. It iscontemplated that more and/or fewer holes 113 can be used to assemblerear grill 110 to body 120.

As shown, support channels 114 a, 114 b, 114 c and 114 d extend outwardfrom motor interface 118 and connect to perimeter rail 112. It iscontemplated that multiple support channels 114 may extend from motorinterface 118 and connect at a plurality of locations along perimeterrail 112. In a non-limiting fashion four support channels 114 are shown.

In a preferred embodiment, motor interface 118 is substantially circularin shape as defined by circumference 118 a. In one exemplary embodiment,circumference 118 a of motor interface 118 is approximately the samesize as hub 142 of impeller 140, see FIG. 2. Located proximate thecenter of motor interface 118 are motor cooling openings 118 b. In oneexemplary embodiment, openings 118 b are substantially aligned withventilation openings 138 of rear end bell 134 of motor 130, see FIG. 2.Openings 118 b may include grill elements 118 c. The shape and size ofcircumference 118 a, motor cooling openings 118 b and grill elements 118c are utilized to allow motor interface 118 to function as an airimpedance shield as per U.S. patent application Ser. No. 10/903,061,filed Jul. 30, 2004, which is hereby incorporated by reference into thispatent application in its entirety.

Also shown is a plurality of motor mounting holes 111. In a preferredembodiment, the number of motor mounting holes 111 is about four;however, the invention is not so limited. It is contemplated that anynumber of motor mounting holes 111 may be used.

Vertical and horizontal grill elements 116 define flow through openings117. Although grill elements 116 are shown horizontal and verticallyorthogonal to one another the invention is not so limited. It iscontemplated that other shaped such as arcuate shaped and radiallyoriented grill elements may be used.

FIG. 3B is a partial cross section view cut through support channel 114of the rear grill 110 of FIG. 3A. As shown, support channel 114 includesrecess 306 and walls 115 a and 115 b. The use of walls 115 a and 115 bincrease the structural integrity of support channel 114 and enhance theability of rear grill 110 to support the weight and dynamic forces ofmotor 130 and axial air impeller 140. Support channel 114 may also beused as a conduit for wires 304. Wires 304 electrically connectcomponents of box fan 100 such as, for example, control 160, motor 130and power cord 105. Clips 302, used to retain wires 304 within space 308of support channel 114 can be molded integral to support channel 114 orbe a separate component. Although support channel 114 is shown having asubstantially rectangular cross sectional form the invention is not solimited, it is contemplated that the cross sectional form of supportchannel 114 may include triangular and arcuate forms as well.

FIG. 3C is a partial cross section view cut through perimeter rail 112of rear grill 110 of FIG. 3A. Perimeter rail 112 as shown supports thevertical and horizontal grill elements 116 of rear grill 110. The crosssectional form of perimeter rail 112 includes walls 112 a, 112 b and 112c. The substantially orthogonal and parallel relationships of walls 112a, 112 b and 112 c increase the structural integrity of perimeter rail112.

FIGS. 3D and 3E show a partial cross sectional side view and a partialfront view respectively of an alternate embodiment for the perimeterrail. As shown, perimeter rail 312 includes recess 315, walls 316 a, 316b, 316 c and angular ribs 318. As shown in FIG. 3E, angular ribs 318 areoriented at an angle relative to walls 316 a, 316 b and 316 c and serveto connect walls 316 a, 316 b and 316 c together. The use of walls 316a, 316 b and 316 c in conjunction with ribs 318 increase the structuralintegrity of perimeter rail 312 and enhance the ability of rear grill110 to support motor 130 and axial air impeller 140 via support channels114.

FIG. 4 is a rear perspective view of rear grill 410. Rear grill 410 isan alternative embodiment for rear grill 110 of FIG. 3A. As shown, reargrill 410 uses horizontal structural supports 402 and verticalstructural supports 404 to enhance the structural integrity of motorinterface 118. Horizontal structural supports 402 and verticalstructural supports 404 are used in lieu of support channels 114, asshown on rear grill 110 of FIG. 3A. Horizontal structural supports 402and vertical structural supports 404 may be constructed dimensionallythicker than grill elements 116 while not overtly departing from thehomogeneous appearance of grill elements 116. In other respects, reargrill 410 may be similar to the embodiment of rear grill 110 of FIG. 3A.

FIG. 5 is a rear perspective view of rear grill 510. Rear grill 510 isan alternative embodiment for rear grill 110 of FIG. 3A. As shown, reargrill 510 uses radial structural supports 502 to enhance the structuralsupport of motor interface 118. Another aspect of rear grill 510 thatcontributes to the structural support of motor interface 118 are thesubstantially concentric arcuate grill elements 516. Radial structuralsupports 502 and substantially concentric arcuate grill elements 516 areused in lieu of support channels 114, as shown on rear grill 110 of FIG.3A. Radial structural supports 502 may be constructed dimensionallythicker than grill elements 516 thus enhancing their structure withoutdeparting from the homogeneous overall appearance of rear grill 510. Inother respects, rear grill 510 may be similar to the embodiment of reargrill 110 of FIG. 3A.

FIGS. 6A, 6B and 6C are rear, top and side views of box fan 600. Box fan600 utilizes rear grill 610. Rear grill 610 has a spherical form asdefined by spherical radius R in both top view FIG. 6B and side viewFIG. 6C. Spherical radius R of rear grill 610 increases the overallrigidity of the structure supporting motor interface 118. As shown,radius R is convex relative to body 120, however the invention is not solimited. It is contemplated that spherical radius R may be concaverelative to body 120.

In the illustrated embodiment of rear grill 610, support channels 114are used. It is contemplated that other support structures such as, forexample, horizontal structural supports 402 and vertical structuralsupports 404 of FIG. 4 and/or radial structural supports 502 andsubstantially concentric arcuate grill elements 516 of FIG. 5 may beused in conjunction with spherical radius R. In other respects, box fan600 may be similar to box fan 100 of FIG. 1.

FIG. 7 shows in a non-limiting fashion other features that can beincorporated into box fan 700. As shown, FIG. 7 handle 760 is anintegral part of rear grill 710. This has the advantage of not requiringthe additional component and assembly of handle 160 as shown in FIG. 1.

Also shown in FIG. 7 is control 762. Control 762 is located near motor130 and is allowed access to motor 130 through rear grill 710. Thisfeature has the advantage of eliminating the a control wire (not shown)required to connect motor 130 to control 162 located at a more remotelyas shown in FIG. 1. This feature also allows control 762 and motor 130to be pre assembled as a sub assembly bringing further advantages to theassembly process.

In the illustrated embodiment of rear grill 710, support channels 114are used. It is contemplated that other support structures such as, forexample, horizontal structural supports 402 and vertical structuralsupports 404 of FIG. 4 and/or radial structural supports 502 andsubstantially concentric arcuate grill elements 516 of FIG. 5 may beused in conjunction with handle 760 and control 762. In other respects,box fan 700 may be similar to box fan 100 of FIG. 1.

As described and shown, box fan 100 utilizing motor interface 118incorporated into polymer rear grill 110 eliminates the need for metalmotor mounting brackets and the additional labor to assemble the metalbrackets used on a conventional box fan. This reduces the final cost ofthe box fan. Another advantage of incorporating motor interface 118 intorear grill 110 is the ability of the polymer material of rear grill 110to electrically isolate motor 130 from external metal components of boxfan 100 such as, for example, the body 120.

As described and shown, body 120 of box fan 100 is substantially thesame as the body used on a conventional box fan. The similaritiesbetween body 120 of box fan 100 and the body used on a conventional boxfan allow the manufacturer to easily alternate between the production ofbox fan 100 with motor interface 118 and the production of aconventional box fan with metal brackets. The ability to alternateproduction allows the manufacturers to respond to material costs andproduce the box fan that yields the most cost savings.

As described and shown, the use of the polymer rear grill to support themotor can also incorporate other features within the structure such as,for example; handles, switches, improved cooling features, etc. Thecombination of these features and the motor support incorporated intothe rear polymer grill of the box fan yield further cost savings for theuser.

The box fan structure as described will maintain or improve the qualityand safety of the device while permitting the manufacturer theflexibility of production to produce the device at a lower cost.

Although the invention has been described with reference to exemplaryembodiments, it is not limited thereto. Rather, the appended claimsshould be construed to include other variants and embodiments of theinvention, which may be made by those skilled in the art withoutdeparting from the true spirit and scope of the present invention.

1. A box fan comprising: a fan body formed of metal comprising: at leastone wall forming a substantially polygonal shape having a rear bodyopening and a front body opening substantially parallel to said rearbody opening and located on the opposite side of said fan body from saidrear body opening; a unitary rear grill formed of polymer disposedproximate and substantially covering said rear body opening, saidunitary rear grill comprising; a perimeter rail defining extents of saidunitary rear grill; a plurality of grill elements defining flow throughopenings, said flow through openings allowing air to pass through saidunitary rear grill; an integrated motor interface structuresubstantially centered with reference to said extents of said unitaryrear grill; a front grill disposed proximate and substantially coveringsaid front body opening; an interior space defined by said at least onewall of said fan body, said unitary rear grill, and said front grill; amotor having a shaft extension disposed within said interior space, saidmotor being connected to and structurally supported by said integratedmotor interface structure of said unitary rear grill; and an axial airimpeller disposed within said interior space, said air impellercomprising; a hub connected to said shaft extension of said motor; aplurality of blades extending radially outward from said hub.
 2. The boxfan of claim 1, wherein said unitary rear grill further comprisessupport channels extending from said motor interface structure to saidperimeter rail of said unitary rear grill, said support channelsstructurally support said motor and said axial air impeller.
 3. The boxfan of claim 2, wherein said support channel further defines a conduitand electric conducting wires of said box fan are located in saidconduit.
 4. The box fan of claim 2, wherein perimeter rail, grillelements, motor interface, and support channels are a single moldedpolymer part.
 5. The box fan of claim 4, wherein said single moldedpolymer part electrically isolates said motor from all external surfacesof said box fan.
 6. The box fan of claim 2, wherein said support channelfurther comprises at least one wall defining a recess.
 7. The box fan ofclaim 1, wherein at least a portion of said plurality of grill elementsextend from said motor interface structure to said perimeter rail ofsaid unitary rear grill and said portion of said plurality of grillelements structurally support said motor and said axial air impeller. 8.The box fan of claim 1, wherein said unitary rear grill comprises aspherical form as defined by a surface of the rear grill, wherein saidsurface comprises a spherical radius.
 9. The box fan of claim 1, whereinsaid motor further comprises a rear end bell including ventilationopenings and said integrated motor interface further comprises: a motormounting surface; and a cooling opening substantially centered in saidmotor mounting surface; wherein said ventilation openings of said rearend bell and said cooling opening in said integrated motor interface aresubstantially aligned.
 10. The box fan of claim 9, wherein said hub ofsaid axial air impeller further comprises a first circumferentialperiphery and said motor mounting surface is defined by a secondcircumferential periphery and said first and said second circumferentialperipheries are substantially aligned.
 11. The box fan of claim 1,wherein said integrated motor interface structure further comprises aplurality of motor mounting holes.
 12. The box fan of claim 1, whereinsaid unitary rear grill further comprises a unitary handle.
 13. The boxfan of claim 1, further comprising a controller wherein said motor andcontroller is accessible through said unitary rear grill.
 14. The boxfan of claim 13, wherein said unitary rear grill further comprises ahandle as an integral part of said unitary rear grill.
 15. The box fanof claim 1, wherein said perimeter rail further comprises: a first wallsubstantially parallel to said grill elements; a second wall extendsubstantially orthogonal and outward from said first wall; and a thirdwall extending substantially orthogonal from said second wall.
 16. Thebox fan of claim 1, wherein said rear grill perimeter rail furthercomprises: a first wall substantially parallel to said grill elements; asecond wall extending outward from said first wall; a recess formed insaid second wall; a third wall extending from said second wall, saidthird wall oriented substantially orthogonal to said first wall; andangular ribs extending between said first wall and said third wall, saidangular ribs connecting said first wall, said second wall, and saidthird wall.
 17. The box fan of claim 1, wherein said rear grill furthercomprises: horizontal structural supports extending from said integratedmotor interface to sides of said perimeter rail; and vertical structuralsupports extending from said integrated motor interface to a top and abottom of said perimeter rail.
 18. The box fan of claim 17, wherein saidhorizontal structural supports and said vertical structural supports areconstructed dimensionally thicker than said grill elements.
 19. The boxfan of claim 1, wherein said rear grill further comprises: a pluralityof substantially concentric arcuate grill elements; and radialstructural supports extending radially from said integrated motorinterface to said perimeter rail, said radial structural supportsconnected to said concentric arcuate grill elements.
 20. A box fancomprising: a fan body formed of metal comprising: at least one wallforming a substantially polygonal shape having a rear body opening and afront body opening substantially parallel to said rear body opening andlocated on the opposite side of said fan body from said rear bodyopening; a unitary rear grill formed of polymer disposed proximate andsubstantially covering said rear body opening, said unitary rear grillcomprising; a perimeter rail defining extents of said unitary reargrill; a plurality of grill elements defining flow through openings,said flow through openings allowing air to pass through said unitaryrear grill; a substantially circular-shaped integrated motor interfacestructure substantially centered with reference to said extents of saidunitary rear grill; support channels extending between and connectingsaid motor interface structure to said perimeter rail of said unitaryrear grill; a front grill disposed proximate and substantially coveringsaid front body opening; an interior space defined by said at least onewall of said fan body, said unitary rear grill, and said front grill; amotor disposed within said interior space, said motor being connected toand structurally supported by said integrated motor interface structureof said unitary rear grill, said motor having a shaft extension; anaxial air impeller disposed within said interior space, said airimpeller comprising; a hub connected to said shaft extension of saidmotor; a plurality of blades extending radially outward from said hub.21. A box fan comprising: at least one wall formed of metal forming asubstantially polygonal shape; a rear opening formed by said at leastone wall; a front opening formed by said at least one wall, said frontopening oriented substantially parallel to said rear body opening andlocated on the opposite side of said at least one wall; a front grilldisposed proximate and substantially covering said front opening; aplurality of front grill elements defining front flow through openings,said front flow through openings allowing air to pass through said frontgrill a rear grill disposed proximate and substantially covering saidrear opening; a perimeter rail defining extents of said rear grill; aplurality of rear grill elements defining rear flow through openings,said rear flow through openings allowing air to pass through said reargrill; a substantially circular shaped integrated motor interfacestructure substantially centered with reference to said extents of saidrear grill; motor cooling openings in a center region of said integratedmotor interface structure; support channels extending outward from saidmotor interface structure and connect to said perimeter rail; whereinsaid rear grill, said perimeter rail, said rear grill elements, saidmotor interface, and said support channels are a single molded polymerpart; an interior space defined by said at least one wall of said fanbody, said front grill, and said rear grill; a motor disposed withinsaid interior space, said motor being connected to and structurallysupported by said integrated motor interface structure of said reargrill; a shaft extending from said motor; a rear end bell of said motor;ventilation openings in said rear end bell, wherein said ventilationopenings of said motor rear end bell substantially align with said motorcooling openings in said integrated motor interface structure; an axialair impeller disposed within said interior space; a substantiallycircular shaped hub of said air impeller connected to said motor shaft,wherein a circumference of said substantially circular shaped hub issubstantially equal to said substantially circular shaped integratedmotor interface structure; and a plurality of blades of said airimpeller extending radially outward from said hub.